For humans the underwater environment is hostile and continued existence underwater require special means, mainly for providing breathing air underwater. Thus all actions taking place underwater include certain risks for humans. When these risks are combined with the natural fear that majority of humans have for deep underwater places, most people never try any kind of underwater activities.
Thus there is a need for arrangements that provide possibility for people to try out or to train various underwater activities without the major risks and fears associated to these types of activities.
Further, any activities or sports taking place underwater are somewhat problematic in view of the spectators.